Thermal conductivity of aerated concrete (AC) composites containing micro-encapsulated phase change materials

Aerated concrete (AC) was incorporated with micro-encapsulated phase change materials (PCMs) to form a novel PCM-composite AC with improved thermal storage capacity. RT25 paraffin was selected as the PCM and the composite materials were prepared by adding micro-encapsulated paraffin as an ingredient at various loadings. The effective thermal conductivity of the composite samples was measured at both 17 ºC and 35 ºC, while the paraffin was in solid and liquid phases, respectively. The volumetric heat capacity of the composites were also measured. Results showed that both the thermal conductivity and volumetric heat capacity increase upon adding the micro-encapsulated paraffin. However, they were found to decrease when further increase the paraffin loading. The maximum thermal conductivity and volumetric heat capacity were enhanced by approximately 35% and 30% when the paraffin loadings were 1% wt. and 3% wt., respectively. Since the increase of thermal conductivity leads to the deterioration of the thermal insulation performance, the composite samples with 3% wt. micro-encapsulated paraffin with lower thermal conductivity but the highest volumetric heat capacity was exhibited to be more appropriate